Rheologically Determined Phase Diagram and Dynamically Investigated Phase Separation Kinetics of Polyolefin Blends

摘要

Phase separation behavior of polymer blends and polymer solutions has long attracted the interest from fundamental and industrial viewpoints, since a lot of physical problems are not well understood1-2. Rheology as a sensitive tool to study the phase behavior of polymer blends has been widely used for several decades. In this study, the polyolefin blends of PEH and PEB were investigated because of it's widely application and commercial prospect in industry. PEH/PEB blends have been proved to be an UCST system, and the phase diagram of which has been fundamentally calculated from Flory- Huggins theory by Wang et al3. The researchers have used indirect methods such as diffuse light scattering to identify the phase boundary by cooling the sample from the melt to crystallization temperature. However, the spinodal line of the phase diagram of PEH/PEB blends was just theoretically calculated and there is still a lack of the experimental evidence. Therefore, in this work, the rheological measurement will offer useful supports to elucidate the phase separation and crystallization behaviors from molecular dynamic viewpoints.